Devonian tectonism of the Illinois basin region, U.S. continental interior

A synthesis of surface and subsurface data for the Illinois basin and its margins demonstrates that tectonic activity occurred in this intracratonic region throughout the Devonian. This activity is manifested by uplift of domes and arches, subsidence of the Illinois basin, and high-angle faulting and formation of forced folds. Most of the structures active during the Devonian were also active before and/or after the Devonian, and thus represent long-lived crustal weaknesses. Available data, although not sufficient to provide tight constraints on the duration of activity for specific structures, do hint that the style and location of Devonian tectonism changed between the Early and Middle Devonian. For most of the Early Devonian, the margins of North America were not major collisional orogens, so the occurrence of deformation in the Illinois basin region during this time suggests that intracratonic tectonism can take place in the absence of collisional boundary loads at the continental margin. The possible change in style and location of deformation that occurred in the late Early Devonian suggests that a change in the continental stress field occurred at that time, perhaps related to the onset of the Acadian collision.